Remember Spencer Pratt and Heidi Montag? The villainous duo of MTV's "The Hills" who were so very famous, at least for a time, for simply being famous, recently gave an interview to The Daily Beast, in which they discuss their regrets. They have a few: Among them, Montag says she wishes she hadn't had so many cosmetic procedures.

“Obviously I wish I didn’t do it,” Montag tells the online magazine. If you'll recall: The now-25-year-old has had breast implants, rhinoplasty, liposuction, collagen injections in the lips, a chin reduction, a brow lift and a buttock augmentation, among
other procedures
.

We wondered: How often are regrettable cosmetic surgeries redone — or even "undone"?

"Redos are very, very common," explains Dr. Tony Youn, a Michigan-based, board-certified plastic surgeon and contributor to msnbc.com. In fact, Youn says up to 20 percent of the patients he sees are people seeking some kind of "redo" — usually, it's a correction or improvement to rhinoplasty or breast augmentation.

There aren't many statistics to come by in terms of cosmetic surgery "redos." But the American Society of Plastic Surgeons has this to offer: In 2010, there were 21,714 breast implant removals among augmentation patients. No figures exist that describe the number of "undos" — but that's likely because, in terms of cosmetic surgery, what is done usually can't be "undone."

With breast augmentations, in particular, "typically, the changes that happen to a breast, they are permanent. So if you take the implant out, the skin ends up being stretched out," Youn explains. "If Heidi ends up taking them out, her 700 CC implants — almost the biggest size that we make — if they take them out of her breasts, she's going to have two basically empty sacs."

Youn says the most common procedure his patients want redone are nose jobs. Judging from his own patients, he estimates that up to 25 percent of patients who have rhinoplasty surgeries eventually want something corrected — either they feel their nose has changed too much and they no longer look like themselves, or it hasn't changed quite enough.

Of course, things like Botox or Montag's collagen injections are temporary, lasting about four to six months, so her lips have likely depuffed by now. But it gets sketchier when we get into some of the other cosmetic surgeries Montag's had: If she regrets her chin reduction, for example, the only way to fix that would be to put an implant in. And the only way to "undo" a liposuction procedure is to gain weight — or have fat injected back in, Youn explains.

The lesson here: With plastic surgery, as with life, there really is no CTRL+Z.

Reese Witherspoon, 34

We asked msnbc.com contributor Dr. Tony Youn, a Michigan-based, board-certified plastic surgeon who has been featured on "Dr. 90210" and runs a popular celebrity cosmetic surgery blog, to weigh in with his predictions of how these still-young celebrities will fare in the years to come. He's also identified areas on their faces that will either be assets or obstacles to aging well.

Dr. Youn, who hasn't treated any of those featured, shares his observations:

This “Legally Blonde” star will always look youthful. Women with rounder faces, like Reese, typically are much slower to show their age than women with longer faces, since they tend to retain the fullness and softness of youth. It doesn’t appear that Reese has had any significant anti-aging treatments short of sunblock and clean living, and she likely won’t want (or need) anything more than this for a long time.
(Nick Haddow / Getty Images; msnbc.com illustration)
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Lindsay Lohan, 23

Too much alcohol: check. Smoking: check. Personal drama: check. Over plumping of the lips: check. Drugs: check. Everything Lindsay can do to make herself look older, she appears to be doing. Her skin is aging well past her 23 years, notable in the lines under her eyes and on her forehead. At this rate in 10 years she may look double her age! Lindsay appears to be a good example of a bad lifestyle leading to premature aging.

Due to her fair complexion, her skin is as freckled and sun-damaged as a person in her mid-40s. I would strongly recommend that Lindsay visit a therapist to get her life in order and avoid all the vices I’ve listed above. A powerful sunblock, like Antihelios SPF 60 by La Roche Posay, would be helpful too.
(Thibault Camus / AP; msnbc.com illustration)
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Jake Gyllenhaal, 29

No matter what role Jake plays, people fall in love with him. He has his own unique, boyish look, which I predict will keep him staying youthful, Dick Clark-style. One big reason is his upturned corners of his mouth -- they create a perpetual smile that women adore. Combine that with his thick eyebrows, piercing eyes, and just-a-bit-too-long nose, and the sum of the parts is a Prince of Hollywood who will keep back the "Sands of Time."
(Stefan Wermuth / Reuters; msnbc.com illustration)
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Gwyneth Paltrow, 37

Like a fine wine, Gwyneth is better and better with age. Her combination of high cheekbones, angular face, and flawless skin will keep her looking youthful well into her 40s, although lines are visible under her eyes. But while her angular features are currently a blessing, as she ages into her 60s, this can actually result in premature aging by making her look gaunt. She could help combat in future years by softening her face using facial fat grafting, where fat is taken from the thighs and injected into the face. Cost of facial fat grafting: $3,500.
(Mario Anzuoni / Reuters; msnbc.com illustration)
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Anne Hathaway, 27

Anne Hathaway is one of the few young stars who exudes classy Hollywood glamour. She seems to combine unquestionable beauty with a girl-next-door attitude. She’s been blessed with full lips, a heart-shaped face, and round cheekbones, all of which seem natural and will keep her looking youthful and glamorous as the decades pass. With her understated grace, this Hollywood “Princess” just might become this generation’s Audrey Hepburn. I wouldn’t recommend anything for her except good medical grade skin care such as the Obagi C-RX system.
(Brian Snyder / Reuters; msnbc.com illustration)
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Josh Holloway, 40

Josh is the quintessential bad boy who women love. One look at him and women get “Lost” in his good looks. He is currently at that age where he’s young enough to still be considered cool and youthful, but old enough that women of all ages find him attractive. The greasy hair, unshaven appearance, and intense frown lines are no match for his natural charisma, strong jaw and built physique. I hope, like any good actor who’s spent a lot of time filming in Hawaii, that he’s been wearing good sunblock. Other than that, his strong facial bone structure will keep him looking handsome and rugged for decades to come. If I had to recommend one treatment for Josh, Botox could ease those frown lines between his eyes, which will deepen over time. Cost of Botox: $500.
(Hector Mata / AFP - Getty Images; msnbc.com illustration)
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Pamela Anderson, 42

What happens when a real-life Barbie doll turns 42 but still tries to look like she’s 25? Pamela’s combination of flowing blonde hair, plumped-up lips, massive bosom and tiny waist have made her an icon. But we’re now seeing the effects of the years, the partying, the surgeries and the sun. She’s starting to look someone desperate to fight the years. For most people I recommend that “less is often more,” but in Pam’s case “more has always been more.” If she continues with this approach, the coming years won’t be kind.
(Gabriel Bouys / AFP - Getty Images; msnbc.com illustration)
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Maggie Gyllenhaal, 33

Maggie Gyllenhaal has one of Hollywood's most unique looks. Her combination of a “Crazy Heart”-shaped face; round, button nose; and full, turned-up-at-the-corner lips make her a real beauty. As long as she doesn't walk into the wrong plastic surgeon's office, she's going to look glamorous for decades to come. I would recommend that she keep her skin looking youthful with mild, noninvasive anti-aging treatments such as the Cynosure Laser Facial.
(Andrew H. Walker / Getty Images; msnbc.com illustration)
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Tyrese Gibson, 31

Tyrese is the total package. Not many people can claim to be a successful singer, rapper, actor and model, but he can. He appears to be a perfect male specimen, from the top of his slightly pointy bald head to his amazingly ripped body. In addition, his skin is flawless, and the envy of men and women everywhere. As long as he keeps himself in shape, eats right, and avoids some of the Hollywood vices that other celebs succumb to, he should continue to look great for years to come.
(Jason Merritt / Getty Images; msnbc.com illustration)
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Britney Spears, 28

Oops, she did it again. Britney Spears polished off another Toxic Big Mac combo meal. Britney’s only 28 but already appears to be struggling to keep looking as good as she once did. It’s not helping that she engages in activities that will prematurely age her: she smokes, she drinks and she eats fast food. Her weight has fluctuated immensely, and she has a partial double chin which has become fodder for paparazzi photos. The salt and fat in fast food can result in adult acne, weight gain and worsening cellulite. If Britney could just refocus on her family, her health and her career (in that order) and avoid all of the above vices, she just might return to the form that made her one of the sexiest women alive and be able to slow time’s toll.
(Larry Busacca / Getty Images; msnbc.com illustration)
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Halle Berry, 43

This Catwoman looks like she has nine lives -- she just doesn’t age. Her skin is flawless and she has a classically beautiful face, with full lips, striking brown eyes and full cheeks. While stress has been a proven predictor of premature aging, the stress of her many failed romantic relationships does not seem to have taken a toll on her good looks. She’ll continue to age well, but a little Botox and filler like Juvederm may keep her looking smooth and wrinkle-free. For her, I’d recommend the eMatrix by Syneron, which tightens and smooths. Cost of eMatrix by Syneron: $750 per treatment.
(Bryan Bedder / Getty Images; msnbc.com illustration)
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Paul Walker, 36

Paul's aging process is definitely not “Fast and Furious.” This 36-year-old actor has a chiseled face, with a strong brow and chin, contributing to his masculine look. While overall he has classic Hollywood handsomeness, the one drawback I see in his aging is his hairline. He has a bit of a high forehead, which may further recede in the future, causing him to look older and older. If this happens, he can fight time’s effects by avoiding the comb-over and opting instead for hair transplant surgery (such as appears to be the case with Mel Gibson) or go completely bald (like Bruce Willis). Cost of hair transplant surgery: $4,000-$10,000.
(Frederick M. Brown / Getty Images; msnbc.com illustration)
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Tara Reid. 34

Tara is an example of the effects of too much partying, smoking and the California sun. She may have once been the quintessential beach blonde, but unfortunately this “American Pie” actress has already aged past her fresh date. Her glamorous looks have been tainted by years of abuse. But, unlike some of her contemporaries, she doesn’t appear to have had any facial plastic surgery so, there’s still hope for her. Her soft cheeks, pouty lips, and pretty doe eyes haven’t been touched, and form the basis for her beauty. Clean living, a healthy diet and a series of laser treatments such as the Cynosure Laser Facial can help return her to her former beauty and can slow down her accelerated aging. Cost of Cynosure Laser Facial: $200 each.
(Frederick M. Brown / Getty Images; msnbc.com illustration)
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Hayden Christensen, 29

Youthful good looks. Money. Fame. Talent. A major role in the greatest movie series of all time: “Star Wars.” No wonder women love him and men want to be him. Hayden is a young Hollywood Adonis, with a baby face that will age well over the next few decades. He has a nice head of hair, piercing eyes, full lips and just a little roundness at the tip of his nose, causing him to look like the boy next door that all the girls want to date. Guys like him make normal guys like me look bad.
(Larry Busacca / Getty Images; msnbc.com illustration)
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Megan Fox, 24

Megan Fox is her generation’s Angelina Jolie. She’s a huge star, has tattoos that give her a dangerous vibe and is almost impossibly beautiful. So beautiful, in fact, that she almost looks manufactured, or "Transformed." Her cheekbones are perfect, her nose is perfect, and her figure is perfect. I believe that she’s had a nose job (rhinoplasty), lip injections and a breast augmentation to take her beauty into the stratosphere. But enough is enough. My recommendation for her is to be very selective on any further cosmetic surgery or, as she ages, she could end up looking like a caricature of herself. As a plastic surgeon it’s much easier to take a “10” and drop her to a “7” than it is to take a “10” and make her a “10.5.”
(Darren Calabrese / AP; msnbc.com illustration)
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Charlie Sheen, 44

Charlie has had enough drama in his life for two and a half men, much less just one. A recent study proved that stress can cause premature aging. In Charlie’s case, the stress and drama of his personal relationships may have taken their toll. While he appeared to have stopped the aging process for most of the late '90s and early 2000s, his face is becoming more drawn and gaunt and showing more wrinkles, particularly around his eyes. The main thing I would recommend for Charlie to keep aging at bay is to get himself into a stable, drama-free relationship. Otherwise, while some have accused him of having hair plugs, I’ve not seen any definitive evidence of this. I bet he’s stayed away from the plastic surgeon’s knife … so far.
(Chris Pizzello / AP; msnbc.com illustration)
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Natalie Portman, 28

I believe Natalie Portman is the most beautiful actress alive today. Her high cheekbones, perfect lips, wonderful skin and chiseled facial structure give her a glamorous Hollywood look rivaled by few. On top of that, she’s an Ivy League grad and her rare combination of beauty and brains put her at the top of my list of celebrity bachelorettes. As she gets older, her face will likely age by becoming thinner and gaunter but she’ll likely remain a classic beauty. One way to fight this aging process is to use injectable plumpers, like Sculptra. For now, though, she needs only continue the healthy vegan lifestyle she currently has. "V for Vendetta"? How about B for Beautiful! Cost of Sculptra: $1,000 per session.
(Astrid Stawiarz / Getty Images; msnbc.com illustration)
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